Distillation and condensation system for converting salt water to fresh water



Aug. 13. 1968 w. 1.. BOURLAND 3,397

DISTILLATION AND CONDENSATION SYSTEM FOR CONVERTING SALT WATER 'IO FRESHWATER 6 Sheets-Sheet 1 Filed April 21, 1967 W NM KMmZNQZDQ m2: fimhS533. I I III III H @w m l lu l l l i l HM IH IQQ\| HI HH l l l .l

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Aug. 13. 1968 w. L. BOURLAND 3,397,116 DISTILLATION AND CONDENSATIONSYSTEM FOR CONVERTING WATER SALT WATER TO FRESH Filed April 21, 1967 6Sheets-Sheet 3 INVENTOR.

ATTORNEYS.

Aug. 13, 1968 W. L. DISTILLATION AND CONDENSATION SYSTEM FOR CONVERTINGBOURLAND SALT WATER I'O FRESH WATER Filed April 21. 1967 6 Sheets-Sheet4.

INVENTOR.

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ATTOE/VE United States Patent 3,397,116 DISTILLAT ION AND CONDENSATIONSYSTEM FOR CONVERTING SALT WATER TO FRESH WATER William L. Bourland,North Highlands, Calif. (6350 Everest Way, Sacramento, Calif. 95842)Continuation-in-part of application Ser. No. 544,013, Apr. 20, 1966.This application Apr. 21, 1967, Ser. No. 632,693

14 Claims. (Cl. 202-177) ABSTRACT OF THE DISCLOSURE A condensationsystem and method for the production of fresh water from salt water andthe like which includes an outer vessel which is cooled to condense andcollect vapors, a salt water containing vessel therein, a cylinder witha freely slidable piston inside the salt water containing vessel andelectrical and fluid interconnection systems for supplying steam to theinside cylinder for moving the piston reciprocably therein andcondensing the steam and thereby transferring the latent heatevaporization to the salt water to produce vapor therefrom which iscondensed and collected in the outer vessel and conduit systems for therecovery of fresh water at all stages of one or more such systems isdisclosed.

Cross-reference to related application This is a continuation-in-partapplication of my co-pending application Ser. No. 544,013, filed Apr.20, 1966.

Background of the invention Field of the invention.This inventionrelates to steam condensers and more particularly to steam condensationmethods and systems for converting salt water, brackish water orpolluted water to fresh water.

Description of the prior art.-A large variety of steam generation andcondensation systems for the production of fresh water from salt waterare known. One of the major problems in such systems relates to meansand systems for prevention of scale or the removal of scale from thecondenser parts. Many devices and systems have been proposed to solvethis problem; however, no entirely satisfactory solution has beenproposed. Flash evaporators are satisfactory for many purposes and arewell known in the art but are low in efiiciency especially where steamat a comparatively low temperature is available.

It is known that one of the most serious economic and technical problemsfacing the United States and many parts of the world relates to theproviding of adequate supplies of fresh water for domestic, industrialand agricultural purposes. The problem of providing fresh water inadequate quantities and at a cost which is economically feasible isgenerally attacked from the point of view of providing larger low costsources of energy for the production of steam. There are otherapproaches also to the solution of this serious problem, for example,selective freezing cycles and selective absorption procedures have beenproposed. Much of the effort, however, is directed to finding cheapersources of energy for the production of steam and much of this effort iswasted by ineflicient methods and apparatus for the recovery of theenergy imparted to the steam during the distillation process. Therefore,it is an object of this invention to provide apparatus and methods forhigh efiiciency recovery of energy from steam and for the recovery offresh water thereby.

Summary The objects of this invention include the provision of apparatusfor producing fresh water from steam directly 3,397,116 Patented Aug.13, 1968 and the utilization of the heat evaporization .of such steam toproduce additional fresh water;

The provision of apparatus for causing the expansion of steam and thecondensation of such steam at substantially constant pressure and therecovery .of the heat evaporization of such steam;

A process for the production of fresh water from steam for the recoveryof heat evaporization of the steam by causing the steam to expand andcondense at substantially constant pressure and to transfer the heat ofcondensation to a second body of water to provide additional steam andfresh water therefrom;

The provision of apparatus which is submersible in the ocean or anotherlarge body of water whereby it is possible to utilize the body of wateras a heat sink in the condensation of steam in the production of freshwater;

The provision of a condenser in which the vapor is caused to expand atsubstantially constant pressure and to transfer the heat of vaporizationreleased by the condensation of the vapor to a second volatile materialfor the production of an additional amount of vapor or of a differentvapor and the recovery thereof;

The provision of apparatus in which a vapor is caused to expand atsubstantially constant pressure in a cylinder, the cylinder beingprovided with a freely slidably mounted plug which reciprocably moves inresponse to pressure exerted by the vapor;

The provision of apparatus and methods for the condensation of steam atless than atmospheric pressures and at relatively low temperatures toprevent the formation .of scale;

The provision of systems of pluralities of condensers operating atselected pressures and temperatures dependent upon the source of steamto thereby prevent the forma tion of scale in such condensers; and

The provision of systems and methods including pluralities of condensersoperating from a common source of vacuum.

The above objects broadly encompass the purposes of the invention,however, additional objects reside in the specific constructions,combinations, elements and operating members as shown in the drawingsand described hereinafter.

Specifically summarized, a system which may include one or morecondensers each .of which comprises an inner cylinder which has receivedtherein a freely slidable piston, said cylinder being connected to asource of steam, said piston being reciprocably moved in said cylinderto condense and collect steam, said cylinder being immersed in a body ofsalt water whereby the latent heat of vaporization is transferred to thesalt water to produce vapor therefrom. The vapor from the salt water iscollected in a surrounding condensation vessel and condensed andcollected therefrom. A plurality .of such units may be interconnectedinto a system. In a preferred embodiment of the invention, thecondensation takes place at reduced pressures and consequently atreduced temperatures to prevent the formation of scale on thecondensers. In one embodiment the condensation takes place in theabsence of exterior cooling of the outer chamber and the remaining steamis pressurized and passed to a second stage condenser wherein the sameprocess is repeated and the steam is then passed on to a third condenserand so on as is necessary.

Brief description of the drawing FIGURE 1 is a schematic view of theoverall system for producing fresh water from salt water.

FIGURE 2 is a condenser which is submersible in a large body of waterfor utilizing the body of water as a heat sink and for condensing steamin a two stage condensation process.

FIGURE 2a is a detail cross-sectional view of the wall construction ofthe condenser.

FIGURE 3 is a vertical view of the apparatus of FIG- URE 2 on a reducedscale and in partial cross section taken substantially along line 33 ofFIGURE 2.

FIGURE 4 is a Venturi nozzle for producing a vacuum in the apparatusshown in FIGURE 2 and FIGURE 3.

FIGURE 5 is a valve of the type which may be used in this inventionshown in cross section.

FIGURE 6 is a side elevational view in partial cross section of amodified embodiment of the condenser as shown in FIGURE 2.

FIGURE 7 is a condensation tank interposed in a vacuum line extendingfrom the condenser of FIG- URE 6.

FIGURE 8 is a brine collection tank which is periodically dumped as willbe described and which is connected to the condenser of FIGURE 6.

FIGURE 9 is a modified version of the condenser of FIGURE 6 in which theouter vessel is air cooled.

FIGURE 10 is a modified embodiment of the condenser of FIGURE 9.

FIGURES l1 and 12 are diagrammatic of interconnection systems for aplurality of condensers of the typ shown in the preceding figures.

Description of the preferred embodiments Referring now to FIGURE 1, thesystem includes a steam plant 10. The steam plant may be of aconventional type, for example, it may use such fossil fuels as coal,oil, or gas. It may, in addition, be a nuclear powered steam plant of atype recently proposed. The nature of the steam plant is not importantto this invention.

The steam plant in preferably located on the shore of a large body ofwater 12 which in a preferred embodiment may be a body of salt watersuch as the ocean. It is not an essential part of this invention,however, that the system be located on a large body of water since itwould be possible to substitute the cooling of the body of water, ashereinafter described, by such conventional means as pumps, evaporators,and other equipment known to the art. In addition, the system of thisinvention may be utilized for producing fresh water from brackish wateror from sewage.

Steam is carried by means of a line to the condenser 100 of thisinvention which, in the preferred embodiment, is submerged in the bodyof water 12 and is anchored to the bottom thereof by an anchor member 32which is attached to the condenser by cables 34 and 36. The condenser100 because of its displacement tends to float and will therefore remainin the body of water above the anchor 32.

Fresh water from the condenser is returned by means of a pipe or conduitto a collection station 42 and through pipe 44 to a fresh waterreservoir 46. Of course it will be understood that there may be aplurality of condensers of the type described herein for a single steamplant. It will also be understood that the steam line 30 will beinsulated in the conventional manner. In addition to lines 30 and 40going to the condenser 100, there may be such other lines as arenecessary, for example, the vacuum line 50, the function of which willbe described hereinafter. Additional utility lines and power cables willbe provided in the manner conventional to the art and are not shown onFIGURE 1 for purposes of clarity.

With reference now to FIGURE 2, the structure of the condenser 100 willbe described. Steam enters the condenser from line 30, and fresh waterleaves the condenser 100 through line 40, as shown in FIGURE 1. Vacuumline is also connected to condenser 100 as will be describedhereinafter. Two additional lines, a salt water intake line and a saltwater exhaust line 70, connect to the condenser 100. The interconnectionand function of these lines will be described. Condenser comprises inits major components a wall 102 and a plurality of cooling tubes 104 anda vapor collection dome 106. Included within the condenser is anelongate cylinder 200 enclosing a plug 202 which is slidably mountedwithin the cylinder 200 and which may reciprocably move within thecylinder when pressure is applied unequally to the two sides. Plug 202carries on the opposing sides thereof operating members 204 and 206.Steam may enter the right end of the cylinder 200, as viewed in FIGURE2, by a vent 208 through valve 210 when valve 210 is open. Valve 210 maybe opened or closed by a slide operator 212. The position of slideoperator 212 may selectively actuate electrical sensing device 214, thefunction of which will be described. Without further description it willbe seen that when plug 202 moves to the extreme right of cylinder 200,operating member 206 contacts slide operator 212 on valve 210 and willcause valve 210 to open permitting steam to enter through vents 208.This exerts a pressure against the right side of plug 202 causing it tomove to the left down cylinder 200.

Steam may also enter cylinder 200 at the left end, as viewed in FIGURE2, through vent 209 to valve 220 which is actively opened and closed byslide operator 222 and which carries electrical sensor 224. It will beseen then that plug 202 may move reciprocably within cylinder 200 beingmoved, for example, first to the left by steam pressure entering fromvents 208 until operating member 204 contacts slide operator 222 onvalve 220 opening valve 222. The function of electrical sensors 214 and224 is to electrically close valve 210 when valve 220 is opened byoperating member 204 and, conversely, to close valve 222 when operatingmember 206 contacts slide operator 212 closing valve 210. Valves 210 and220 remain in the open or closed position until operated either byoperating members 204 or 206 or by electrical sensors 214 and 224.Electrical sensors 214 and 224 include solenoid operators and are of atype known to the art. An exemplary valve of this type is shown in FIG-URE 5.

Fresh water, the condenate of the steam which enters cylinder 200, isremoved through exit ports 232 and 234 and through valves 240 and 250respectively. Valves 240 and 250 may be identical and are operated inresponse to the reciprocable movement of plug 202. As plug 202 moves tothe left in cylinder 200 it will move over diaphragm cover 242 andoperate a slide member 244 openmg valve 240 in a manner similar to thatdescribed with respect to valves 210 and 220. The slide operator invalve 240, however, is spring biased in the upward direction holding itin a closed position until a downward force is exerted. Thus when plug202 moves to the left, the downward edge 203 of plug 202 actuates slideoperator 244 opening valve 240, but continued movement to the left ofplug 202 causes the slide operator and the diaphragm cover to return tothe upward position in recess 207 which is in the bottom of plug 202. Atthis point operating member 204 will contact slide operator 222 of valve220 opening valve 220 and causing plug 202 to move to the right. Themovement to the right of plug 202 causes momentary opening of valve 240and forces any remaining condensate through exit port 232. Operation ofvalve 250 by a downward force exerted by the edge 205 of plug 202 ondiaphragm cover 252 causes slide member 254 to open valve 250 causingthe condensed fluid to exit through exit port 234 in the mannerpreviously described with respect to exit port 232 and valve 240. Thereciprocable movement of plug 202 in piston 200, then, is caused byalternately feeding steam to the respective ends of cylinder 200 andresults in removing the condensate alternately from the ends of cylinder200.

The reciprocable movement of plug 202 in cylinder 200 in response to theexertion of pressure by the steam results in the steam being expanded atsubstantially constant pressure. During the expansion at constantpressure, the steam condenses. Cooling is provided on the outside of thecylinder in a manner to be described. Apparatus is provided for carryingout the process of simultaneously expanding steam at constant pressureand condensing the steam at constant pressure and, as will be seen,transferring the heat vaporization to a second media.

In the preferred embodiment the cylinder 200 is elliptical in crosssection. This shape has numerous advantages; for example, the use of anelliptical cylinder and elliptical plug slidably received thereinstabilizes the plugs position so the valves can be actuated by certainaccessories on the plug, for example, operating members 204 and 206. Itwill be understood, of course, that the valving arrangement and theentrance and exit arrangements for the steam and for the condensed freshwater are merely exemplary. Other valves may be substituted withoutdeparting from the intent and spirit of this invention. For example,purely mechanical slide valves could be substituted for valves 210 and220 and a mechanical linkage could be provided between them. Similarly,mechanically operated slide valves of different nature or, valvesactuated electrically or mechanically could be substituted for valves210, 220, 240 and 250. The exact nature of the valves is not anessential part of this invention.

Similarly, the exact shape of the cylinder is not an absolutelyessential part of this invention, however, an elliptical shaped cylinderis preferred.

Cylinder 200 is substantially enclosed in a vessel 300 which ispreferably of a thick insulated Wall structure, shown in FIGURE 2a. Thewall structure may consist of an inner wall 302 and an outer wall 304 ofcorrosion resistant alloy, the intermediate space being filled withinsulation 306. Vessel 300, during continuous operation, is normallyfilled to a level above the top of cylinder 200, the water level beingshown at 308. Salt water enters the condenser 100 through pipe 60 andinto a heat exchanger 400 which has a wall structure of the typedescribed with respect to vessel 300. The salt Water enters at port 402and moves upwardly past heat exchange coils 404 and exits through exitport 406 to one-way valve 408 and a level control valve 410. Valve 410is selectively opened in response to the water level in vessel 300 assensed by float 412 which operates valve 410 by means of rod 414,leveler 416 which is pivotally connected at a fulcrum 418. When thewater level falls below the desired point, float 412 moves out of theopening valve 410 permitting water to flow into vessel 300 to return thewater level to a desired position. In a preferred embodiment, salt watermay be obtained directly from the body of water in which the condenser100 is immersed. For example, if cylinder 100 is immersed in the oceanor a body of salt or brackish water, all that is necessary is to providean opening into pipe 60. It may be desirable to place the opening at aremote location for reasons which will be described later.

Heat is supplied to heat exchanger 400 by causing the condensate fromcylinder 200 to flow through heat exchanger 400. The condensate iscollected from valves 240 and 250 in line 260 and flows through valve420 and through heat exchange coil 404 to pump 430 and then out line 40to the fresh Water reservoir. Valve 420 includes a float 422 which isresponsive to the water level in the valve 420. Pump 430 is actuatedwhen the water level in valve 420 reaches a predetermined level by meansof electrical sensor 424. Electrical sensor 424 operates in a mannersimilar to that described with regard to valve 210 and valve 220, shownin FIGURE 5. It will be seen, then, that pump 430 will operate only whencondensate, fresh water, is being supplied from cylinder 200. Vessel 300is supplied with a port 320 and a flange 322 in which rides a cover 324which may selectively be operated by a steam ram 326 which includepiston 328 which is spring biased to the right my means of spring 330.Steam ram 326 is operated and cover 324 closes vessel 300 when steam isapplied through valve 340. Valve 340 is opened in response to a signalfrom condition responsive element 342, which has sensing elementsthereon 344. Condition responsive element 342 also opens valve 350 toline 70. In the preferred embodiment condition responsive element 342causes valves 340 and 350 to open when the salt concentration in thechamber reaches a predetermined level. Thus, when the salt concentrationreaches a level where evaporation is no longer eflicient, because ofsurface tension, condition responsive element 342 actuates valve 350 toopen the dump line 70 from vessel 300 and valve 340 which closes the topof chamber 300 by means of cover 324. Cover 324 carries on it adownwardly extending protuberance 325 which operates valve 270 by movinghandle 271, of valve 270, to the left, as shown in FIGURE 2. Movement tothe left of handle 271 opens valve 270 permitting steam to flow frominlet 272 or 274 through valve 270 and out exit port 276 into chamber300.

It will be apparent from the foregoing that an apparatus is provided forcarrying out a process wherein steam is caused to expand and to condenseat substantially constant pressure and the heat of vaporization releasedby the condensation of the steam at constant pressure is transferred toa material which is volatile or contains volatile components, forexample, salt Water. The salt water, in the preferred embodiment, iscaused to heat up and to evaporate. The water vapor from the salt waterleaves vessel 300 which selectively communicates with the vesselenclosed by walls 102. The water vapor is then condensed by contact withcooling tubes 104. The water condensate is collected in the bottom ofcondenser and leaves vessel 100 through exit port 110, entering a vacuumtrap 120. In the preferred embodiment the condenser 100 is operated at apartial vacuum to increase the efficiency of the condensation process.The vacuum is caused by exhausting condenser 100 through line 130 whichis attached to the top of condenser 100 in vapor chamber 106. Pipe 130enters trap where the vapors carried past the cooling tubes 104 arecondensed and trapped. The vacuum is provided by exhausting pipe throughline 50 by a vacuum pump which will be described. Fresh water which isproduced by condensing the water vapor on cooling tube 104 and bycondensing the vapors in line 130 is pumped from chamber 120 in pipe 121to pump which is selectively operated in response to float controller142. The fresh water is pumped, by means of pump 140, from trap 120 toline 40 and returns to the fresh water storage system. i

The arrangement of the vapor dome 106 is better shown in FIGURE 3. Line130 carries vapors which are now condensed on cooling tubes 104 to trap120 which is located at the bottom of condenser 100.

Vacuum for condenser 100 may be provided by a vacuum pump located incollecting station 42. While any desired vacuum pump may be used, it isconvenient to use a Venturi vacuum pump to maintain a partial vacuum incondenser 100. Such a Venturi pump is shown in FIGURE 4. In a preferredembodiment it may be desirable to use fresh water from line 40 tooperate the Venturi pump as the fresh water flows from left to right asshown in FIGURE 4, from line 40 through the throat 41 to line 44 andthence to reservoir 46; as shown in FIGURE 1, air, gas, and fluids ingeneral are drawn inwardly at entrance port 43. By this means if anywater vapor is not condensed by the time the vapors leave trap 120, asshown in FIGURES 2 and 3, they will be condensed on route to the pumpingstation or will be condensed upon contact with the now cool fresh water.Of course a rotary vacuum pump or a positive displacement pump may beused to provide the vacuum in place of the Venturi of FIGURE 4.

Referring now to FIGURE 5, a slide valve 400 consisting of a shell 502and a closure member 504 and entrance and exit ports 506 and 508,respectively, is shown. Closure member 504 is operated at one end byslide operator 512 and at the other end by electrical sensor 514. Theelectrical sensor 514 includes sensing contacts 516 and an operatingsolenoid 518. The closure member 504 remains in the position shown untilslide operator 512 is pushed to the right as shown in FIGURE openingvalve 500. Valve 500 then remains open until a current is applied tosolenoid 518 causing closure member 504 to move again to the left in theposition shown. When slide operator 512 is pushed to the right, sensingcontacts '516 are temporarily closed giving a signal to a desired point.With reference to FIGURE 2 again, valve 500 is of the type which may beused as valves 210 and 220. Electrical distributing means are not shownin FIGURES 2 and 3 for purposes of clarity.

Reference is made now to FIGURE 6 which shows an alternative embodimentof condenser 100 which is designated generally as 100a. In condenser1000 the equivalent parts and components are designated the same as inFIG- URE 2 with the addition of the letter a to distinguish the parts.Unless otherwise indicated, the parts are equivalent in the twoembodiments.

Thus, in condenser 100a the steam enters through a pipe 300, the entryof which is controlled by a valve 31a which may be adjusted orcontrolled to permit steam of a desired pressure to pass inwardly. Thesteam passes through valves 210a and 22012 in the manner describedpreviously. The cylinder 200a is substantially identical to the cylinder200 with the exception that it may, in a preferred form, include aplurality of cooling fins 201a, to increase the efiiciency of transferof heat to the reservoir of salt water shown generally at 308a. In thisembodiment, however, the fresh condensed water is removed through valves240a and 250a and exit through the wall of vessel 300a and then directlyin the outer vessel 100a. The water is collected through outlet 110a andis removed by means of pump 140a and line 40a. The salt water entersvessel 300a directly through line 60a and valve 410a.

In this embodiment also, the actuator for 324a is electrically operatedas shown generally at 330a. This electrical actuator may be of thereciprocating solenoid type or may be a rotary electric motor with arotary to linear motion converter or any other type of electricalactuator which ultimately produces a linear reciprocal motion. Sincethis constitutes no essential element of the invention it is not deemednecessary to describe it further.

In the embodiment as shown in FIGURE 6, the cooling water is pumped byconventional means inwardly through tube 104a and thence circulatesthrough tubes 104a and 104a" rather than flowing simultaneously throughthe tubes. In addition, a thick layer of insulation 103a may be providedaround cylinder 102a such as is partially shown in FIGURE 6. Theremainder of the layer of insulation is omitted for clarity ofillustration.

In this embodiment the pressure in the vessel 102a is held as low as ispracticable. Evaporation temperature, for example, of around 100 F. orless in chamber 102a produces excellent efliciency and precludes theformation of scale. A vacuum pump is provided in the outlet line 130a ofvessel 1020. The operation of vacuum pump 150a is controlled by a senser152a which is in the condensing dome and which may sense either thepressure therein or the temperature therein to maintain the desiredoperating pressure in the vessel 102a. Thus, this maintains the pressurein 102a substantially below atmospheric pressure to permit lowtemperature condensation and to thereby prevent the tformation of scalewhich would otherwise result. The brine from vessel 300av is removedthrough valve 3500 to a closed tank 600 by conduit 70a. The pressure intank 600 is maintained in equilibrium with the pressure in condenser1020! by a communicating line 602. The brine is collected in tank 600until float 604 actuates pump 606 to remove the brine through conduit608 and expel it through line 610 into a waste system.

Line 130a passes through a condensing tank 612 to condense any residualvapors in the line and communicates at 131a into a collection vesselwherein the condensed moisture is removed through a line 614 which isvented at 616. The fresh water from line 614, of course, will be fedinto the overall recovery system by any conventional pipe or conduitmeans.

Reference is now made to FIGURE 9 which shows a drawing of a two stagecondenser which operates the same as the one disclosed in FIGURE 6,except that no water cooling is provided in chamber 102b as with respectto condenser a, the components in condenser 100b, except as noted, arethe same as disclosed with respect to condenser 100. In the embodimentof FIGURE 9, the condenser is preferably surrounded by an insulatinglayer 103b which is only partially shown so as to permit the othercomponents to be more clearly illustrated. In this embodiment, the steamenters through line 30b and, as described, reciprocably moves the freefloating piston 20% in cylinder 20% wherein the steam is condensed andthe latent heat of vaporization is transferred to a body of water shownat 30812. The steam produced thereby passes into the outer chamber 102band that portion which is condensed is collected in the collection tankThe steam which is not condensed is pumped out through line 1301) and,in a preferred system, passes to a water cooled condenser such as thatshown in FIGURE 6 designated by 100a. If desired, the steam in line1301) may be pressurized by a conventional pump prior to its entry intothe next stage of condensation. The overall system is describedhereinafter. Any water condensed is carried out through line 40b in themanner previously described.

In addition, a brine tank 600 is provided for interconnection withcondenser 10012 in the manner previously described with respect tocondenser 100a.

Condenser 1000 shown in FIGURE 10, is a two stage condenser thatoperates essentially the same as that shown in FIGURE 9. In thisembodiment, the steam which enters from line 300 through valve 310 iscondensed by reciprocating piston 2020 in the same manner. However, thesteam produced in the body of water designated as 3080 is recirculatedthrough the condensation system by means of a pump 1600 which may returnthe steam at a higher pressure through a valve 1620 and a conduit 1640to the inlet line 300. There will be condensation as a result of thecompression operation and the condensed water is collected in a hold-uptank 1660 and intermittently released by means of a float valve 1680disposed therein. The condensate passes into the vessel 1020 throughconduit 1700. In a completely closed system of this type air lockingwould ultimately occur if the air and gases present in the steam are notexhausted from the system when they be come excessive. The firstindication of too much air in the system would be a rise in pressure inthe line 300 and in 1300 due to the elasticity of the air present in thecylinder. At this point it is desirable to vent the entire gas systemand this is done by means of valve 1620 and outlet conduit 1720. Ifdesired, this may be done by a control 1740 at timed intervals oraccording to a sensed physical property such as pressure or change inpressure, etc.

The valve comprising catch tank 1660 and float 1680 are merely exemplaryof valves of this type and any valve which may operate generallyequivalently will be satisfactory in this operation. Timed intervalvalves could also be use-d.

In FIGURE 11, one type of interconnection which may desirably be used isillustrated. A source of steam which may be of any type isinterconnected to a plurality of condensers. First, steam may be fed toa dry condenser of the type shown in FIGURE 9 and designated 1001). Thebrine is removed by the hold-up tank 600 in a manner previouslydescribed and the pressure is maintained in condenser 10% belowatmosphere by a line extending through a condenser 612 of the type shownin FIGURE 7. The output of this condenser may then be fed to one or morewet condensers of the type designated as 100. In this configuration, twosuch condensers are used. It is also noted that additional steam issupplied from the steam source to each of these wet condensers toprovide optimum operating efficiency. Again, the brine is removedthrough a tank 600 in each case and through either one condenser or aplurality of condensers indicated at 612 in the manner previouslydescribed. Obviously, other interconnection systems may be useddepending on the particular circumstances and conditions of operation.

One such alternate interconnection is shown schematically in FIGURE 12.In this system, the steam source feeds in parallel, a plurality of drycondensers. In this configuration, five such dry condensers designatedas 1001) are fed from the steam source. The pressure in these condensersis maintained below atmosphere by a pump 150 and is controlled aspreviously described. The output of pump 150 is fed again to a pluralityof dry condensers, this time three such condensers, designated as Gbwhich are connected in parallel. In a similar manner, pump 150 maintainsthe pressure in these condensers below atmospheric pressure. Again, theoutput of these condensers is fed to a pair of parallel connected drycondensers 10% and the output of these condensers is then ultimately fedto a wet condenser 100a to extract the last remaining fraction of heatenergy in the steam. The output of pump 150 which maintains condenser10001 at a pressure less than atmosphere is passed through a condenser612 to recover any steam still remaining, as previously described. Inthis manner, by using adequate insulation, virtually all the energystored in the steam is recovered and a corresponding quantity of freshWater is produced therefrom.

It is important to realize that by this system the entire condensationof the steam may be carried out in a manner to prevent scale formation.Obviously, the reciprocable movement of the piston 202 prevents scaleformation in the cylinder and the operation of the remaining system at alow pressure and low temperature, say below 160 Fahrenheit, prevents theformation of scale in the remaining portions of the condenser.

It is also important to recognize that while it would be physicallypossible to build individual condensers large enough to handle theentire output of a steam plant, it is highly desirable, in manycircumstances, to provide rather than one large condenser a plurality ofsmaller condensers, such as shown in FIGURE 12, for optimum efficiency.Thus, each condenser which is operating will be operating at its maximumefliciency and if the steam supply becomes diminished to a point whereall the condensers are not needed one of them can be cut out of thesystem with the remaining condensers operating at maximum capacity. Thisprovides for complete flexibility without loss of efficiency.Furthermore, this permits individual condensers to be cut out of thesystem for periodic inspection and preventive maintenance and, whennecessary, for repair.

It should also be understood that while approximately 160 Fahrenheit isa desirable operating temperature under most conditions the maximumtemperature for operation and consequently the maximum pressure must bedetermined for each individual system. Obviously, it is desirable tooperate the system at as high a temperature as it is possible withoutthe formation of scale. The mineral or other content of the water beingtreated must be considered in determining the actual operatingconditions.

Furthermore, it will be realized that it is possible to use highlypurified water, such as distilled water which has been passed throughion exchange columns, etc. to remove all traces of mineral contenttherefrom in the boiler system and recirculating the condensed purifiedwater from the cylinder to the boiler system. Since the entire heatcontent of the steam in the cylinder is transferred to the surroundingbody of water as the piston reciprocates there is no loss of efficiencyas a result of this double cycle.

The utilization of the steam at its maximum efliciency is provided byregenerating the steam to the desired pressure by pumps intermediate aset of cascaded condensers. Such a system is shown in FIGURE 12. Thisnot only forces the steam into the condenser at an optimum pressure butprovides for condensation at a lower temperature to prevent scaling in apreceding condenser or set of condensers.

An apparatus has been disclosed which permits the following process. Avapor may be condensed at substantially constant pressure with the heatof condensation being transferred to a volatile material. The volatilecomponents of the material heated by the condensation of the vapor arethen condensed and collected. While the process and the apparatus havebeen described with particularization to the distillation of salt waterto produce fresh water, it is apparent that neither the process nor theapparatus is limited to this application. Thus the process may be usedto condense any vapor to a liquid and may be used with reference to twoseparate materials where, for example, a first vapor is caused tocondense at substantially constant perssure in the cylinder 200 while asecond material is provided in vessel 300. In this case, the condensatesof the vessel and the cylinder would not be combined. If, however, it isdesirable, the same material may be used in cylinder 200 and vessel 300and the combined condensate collected for use.

The apparatus and process are by no means limited to the production offresh Water from salt water, for example, fresh water may be producedfrom sewage water or from polluted water, however several importantadvantages are apparent with application to the production of freshwater from sea water. For example, the reciprocable movement of plug 202in cylinder 200 maintains the heat exchange walls of cylinder 200 in aclean condition thereby promoting efficient transfer of heat through thewalls. An inspection of the apparatus and a review of the process alsoreveals that essentially of all the energy stored in steam is recovered.This recovery includes the very important heat of vaporization of thesteam. It requires 540 calories to produce a gram of steam and in manydistillation processes this latent heat of vaporization is wasted bypermitting the steam to escape before condensation. The latent heat ofvaporization, in the present process and apparatus, is transferred to asecond body of volatile matter, salt water, where it causes furtherevaporization and subsequent condensation.

As illustrated in FIGURE 1, in the preferred embodiment the condenser issubmerged; however, this is a desirable but not essential part of theinvention. Other variations are possible without departing from thespirit of this invention; for example, the condition responsive sensingelement 342 which, in the preferred embodiment, is sensitive to a saltconcentration which may be sensitive to condensed steam, or otherphysical characteristics or to concentration of materials other thansalt. In addition, while it is inconvenient it would theoretically bepossible to carry out the process in other apparatus; for example, achamber constructed of resilient material which would expand upon theapplication of pressure thereto. Such structures are inconvenient andimpracticable however.

The drawing and specification illustrate a process and apparatus and apreferred embodiment of the invention and will suggest apparatus andmethods which may be used in the apparatus and in the process withoutdeparting from the spirit thereof.

I claim:

1. In a system for producing fresh water from salt Water or the likewhich includes a source of steam and a condenser system for collectingfresh water condensate,

the improvement wherein the condenser system comprises: an enclosedelongate cylinder for receiving steam from said source; a mechanicallyfree, independently movable, plug of a length less than one third thelength of the cylinder and received in the cylinder in essentially fluidtight relation with the inner surface thereof; means connecting thesteam source to the cylinder for supplying steam to the cylinderalternately at the respective ends thereof for causing the plugreciprocably to move in the cylinder, said last mentioned meansincluding valve means operable by the plug for admitting steam into thecylinder as the plug approaches the respective ends of the cylinder;means including a conduit communicating with said cylinder at itsopposite ends for removing steam condensate from the cylinder, valvemeans in said conduit operable by said plug to actuate the same as theplug approaches the respective ends of the cylinder to permit thecondensate to flow from the cylinder to a collector; a vessel formaintaining a body of salt water in heat exchanging relation with theouter surface of the cylinder to absorb the heat released bycondensation of steam in the cylinder; said cylinder being immersed inthe body of salt water, means in said vessel for condensing steamproduced by the heating of the body of salt water, and means forcollecting the condensed steam produced by evaporation of the salt waterbody and passing the same to a collector.

2. The condenser of claim 1 wherein:

the cylinder is elliptical in cross-section and the plug is ellipticalin cross-section for being slidably received in the cylinder.

3. The condenser of claim 1 wherein the vessel for maintaining a body ofsalt water in heat exchanging relation with the cylinder comprises:

a first vessel, having a closable opening therein, substantiallyenclosing the cylinder for maintaining the salt water in contact withthe outer surface of the cylinder to receive the heat released by thecondensation of the vapor in the cylinder.

4. The condenser of claim 3 further comprising:

a second vessel enclosing and in selective communicating relation withthe first vessel to selectively receive steam from the salt water in thefirst vessel when said salt water is vaporized by receiving the heatreleased by the condensation of vapor in the cylinder.

5. The condenser of claim 4 further comprising:

means, including a valve, for selectively exhausting vapors from thecylinder into the first vessel;

a closure member for selectively opening and closing the opening in thefirst vessel, said opening permitting communication between the firstvessel and the second vessel;

means on the closure member for selectively operating the valve foropening the valve when the closure member is closed to therebycommunicate vapor from the cylinder to the first vessel; and

means operably connected with the closure member for draining thematerial from the first vessel when said vapors are communicated theretofrom the cylinder. 6. The condenser of claim 4 wherein the first vesselhas an opening therein for communication between the first vessel andthe second vessel and further comprismg:

sensing means in the first vessel; a dump system for the first vesselincluding a valve for selectively draining the material therefrom;

means operably connected to the sensing means for opening the valve whenthe composition of the material in the first vessel reaches apredetermined condition;

a closure member of the opening in the first vessel;

means operably connected to the sensing means for moving the closuremember to the closed position when said predetermined condition isreached; and

means including a valve disposed for selective operation by the closuremeans for passing vapor from the cylinder to the vessel when thematerial in the vessel reaches said predetermined condition to therebyforceably dump the contents of the first vessel therefrom by said vaporpressure.

7. The condenser of claim 6 further comprising:

vacuum pump means for maintaining the pressure in the second vesselbelow atmospheric pressure.

8. A condenser in a distillation system which comprises:

an enclosed elongate cylinder for receiving distillant vapor;

a plug of less than approximately one third the length of the cylinderreceived in the cylinder forming an essentially fluid tight seal withthe inner surface thereof, said plug being mechanically free andindependently movable in said cylinder;

a first vessel substantially enclosing the cylinder, said first vesselhaving a closable opening therein;

a second vessel substantially enclosing the first vessel, the closableopening in the first vessel permitting selective communication betweensaid first vessel and said second vessel;

means for supplying vapor to the cylinder alternately at the respectiveends thereof for reciprocably moving the plug in the cylinder inresponse to the relative vapor pressures on the respective sides of saidp valve means for alternately removing the condensate from therespective ends of said cylinder, said valve means being operable byreciprocation of the plug to remove the condensate from one end of thecylinder when said plug approaches said end for removing condensate fromthe other end of said cylinder when said plug approaches said other endthereof, said means being constructed to pass the condensate to thesecond vessel;

means for supplying distillant material to the first vessel;

means for maintaining the distillant material in the first vessel to adesired level;

means for selectively draining the distillant material from the firstvessel; and

means for removing condensate from the second vessel.

9. The condenser of claim 8 wherein:

the means for supplying vapor to the cylinder comprises,

conduits in communication with the respective ends of the cylinder,

valves in the conduits,

means extending into the cylinder for actuation by the plug for openingeach of said valves when said actuator is engaged by said plug, saidconduits being in communication with a source of high pressure vapor;

the means for removing condensate from the cylinder comprises,

conduits in communication with the ends of the cylinder,

valves in said conduits for selectively opening and closing saidconduits,

means in the cylinder for actuating said valves for opening the passagein a conduit at one end of the cylinder when said plug approaches saidone end and for opening the passage in the conduit at the other end ofsaid cylinder when said plug approaches said other end of said cylinder,and

pump means in communication with said conduits for withdrawing liquidfrom said cylinder through said conduits;

13 the means for supplying distillant to the first vessel comprises,

a conduit in communication with the said first vessel and with a sourceof said distillant;

the means for maintaining the distillant at a desired level in the firstvessel comprises,

a valve in the last-named conduit, and

sensing means in the first vessel for sensing the level of thedistillant therein, said sensing means being operably connected to saidvalve for selectively opening said valve to permit entry of saiddistillant to maintain said distillant at a desired level in the firstvessel;

the means for selectively removing the distillant from the first vesselcomprises,

means in the first vessel for sensing the composition of the distillantin said first vessel,

a conduit in communication with said first vessel for passing liquidtherefrom,

a valve in the last-named conduit, said valve being operably connectedwith the lastnamed sensing means for being opened when the compositionof the distillant in the first vessel reaches a predetermined condition,

means for selectively closing the opening in the first vessel,

control means operatively connected to the last-named sensing means formoving said closing means to the closed position when the composition ofsaid distillant reaches said predetermined condition,

a conduit system including a valve for passing vapor from the cylinderto the first vessel when said valve is open, and

means on the closing means for opening said valve when said closingmeans is moved to the closed position and for closing said valve whensaid closing means is moved to the open position; and

the means for removing condensate from the second vessel comprises,

a reservoir,

means for passsing the condensate from the second vessel to thereservoir, and

means for pumping the liquid from the reservoir.

10. The condenser of claim 8 further comprising:

vacuum pump means for maintaining the pressure in the second vessel atless than atmospheric pressure.

11. The condenser of claim 10 wherein the vacuum pump means comprises apump interconnected with said second vessel and with the cylinder forpumping the vapors from the second vessel to a higher pressure forpassage into the cylinder.

12. The condenser of claim 11 further comprising:

means for selectively removing accumulated gases from the second vesselfor preventing recirculation thereof through the cylinder; and

means for condensing and collecting vapor condensate from the means forsupplying vapor to the cylinder before such vapor passes into thecylinder.

13. In a salt water conversion plant for producing water of the typewhich includes a steam generator, a condenser, and a collection system,the improvement wherein the condenser comprises: a closed elongatecylinder; a mechanically free, independently movable, plug slidablyreceived in the cylinder forming a seal with the inner surface thereof;means for alternately supplying steam to one end and then to the otherend of the cylinder to cause the plug to reciprocably move while thesteam in the cylinder is being condensed; means for removing thecondensed steam alternately from the respective ends of the cylinder inresponse to the reciprocable motion of the plug in the cylinder; a firstvessel substantially enclosing the cylinder; means for supplying saltwater to the first vessel to cover the cylinder for absorbing the heatreleased by the condensation of the steam in the cylinder as the plugreciprocates in said cylinder, the heat released causing evaporation ofa portion of the salt water in said first vessel; means for selectivelymaintaining salt water in the first vessel at a desired level; and meansfor selectively dumping the first vessel when the salt concentration inthe salt water therein reaches a predetermined value.

14. The invention of claim 13 wherein the first vessel has a closableopening therein and further comprising:

a second vessel enclosing the first vessel, said second vessel beingselectively in communication with the first vessel through said opening;

cooling tubes in the second vessel for condensing vapors therein;

means for selectively closing the opening in the first vessel forselectively preventing communication between said first vessel and saidsecond vessel; and means for maintaining a partial vacuum in the secondvessel.

References Cited UNITED STATES PATENTS 2,185,595 1/ 1940 Kleinschmidt"202-187 X 2,584,211 2/1952 Kraft 202185 X 2,625,506 1/1953 'Baer202185.5 X 2,696,465 12/1954 Kittredge 202185 X 2,760,919 8/1956 Latham202-185 3,206,380 9/1965 Davian 202l 3,290,229 12/1966 Brown 20311 XFOREIGN PATENTS 811,474 4/1959 Great Britain.

OTHER REFERENCES Marks Mechanical Engineers Handbook (6th ed., 1958),sec. 9, pp. 56, 57 and 60.

NORMAN YUDKOFF, Primary Examiner.

F. E. DRUMMOND, Anrz'stant Examiner.

